
#include<stdio.h>

int fib(int n)
{
	if (n == 0) return 7;
	if (n == 1) return 11;
	return fib(n-1) + fib(n-2);
}

int main()
{
	int n = 0;
	scanf("%d", &n);
	printf("%d\n", fib(n));
	
	return 0;	
} 

